NEW YORK (AP) — Major League Baseball umpire Wally Bell, who worked the NL playoff series between the Pittsburgh Pirates and St. Louis Cardinals that ended last week, has died. He was 48.

The commissioner's office confirmed Bell's death Monday. He died of an apparent heart attack in his home state of Ohio.

"All of us at Major League Baseball are in mourning tonight regarding the sudden passing of Wally Bell," Commissioner Bud Selig said in a statement. "I always enjoyed seeing Wally, who was a terrific umpire and such an impressive young man. On behalf of our 30 clubs, I extend my deepest condolences to Wally's family, fellow umpires and his many friends throughout the game."

Bell became the first active MLB umpire to die since John McSherry passed away of a heart attack on the field in Cincinnati on opening day in 1996.

Bell worked the 2006 World Series and three All-Star games, including this year's event at Citi Field, where he was stationed at first base. A veteran of 21 big league seasons, he had also worked four league championship series and seven division series since joining the major league staff in 1993.

According to Bell's biography on MLB.com, his proudest moment as a big league umpire was returning to the field after having open heart surgery in 1999.

"I am deeply saddened and shocked at the loss of umpire Wally Bell," said Joe Torre, MLB executive vice president for baseball operations. "Umpiring was his life, and he touched so many people within the game of baseball. Aside from being an accomplished, All-Star-caliber umpire, Wally was a loving dad to his two teenage children. I extend my deepest condolences to them, his girlfriend Renee, the rest of his family and his admirers across Major League Baseball."

Bell was 34 and 2½ weeks from leaving for spring training in 1999 when his heart problem was detected.

He had quintuple bypass surgery on Feb. 18, 1999, that left him with an 8-inch scar down the middle of his chest. Two of his arteries had been 100 percent blocked. Two more had been 80 percent blocked, another 70 percent.

But he returned to work 11 weeks later in San Diego for a game between the Padres and Atlanta Braves.

That night, plate umpire Mark Hirschbeck took the first ball out of play, and planned to have all the umps sign it before presenting the souvenir to Bell.

Seven years later, Bell was behind the plate for Game 3 of the World Series between Detroit and St. Louis at Busch Stadium.

During the 2013 regular season, Bell was a member of Tim McClelland's crew.

"Wally was a great umpire, a great partner and a great friend. The umpiring community is deeply saddened by this tragic loss. He will be sorely missed by many," said major league ump Joe West, President of the World Umpires Association.